Information is an important commodity in any circumstances. Governments pay high prices for it. Businesses hire special people to take it apart and explain it. Sometimes, intelligence agents die for it.
It’s equally important in a novel. More important, even. Think about it. As an author, you’re not really selling paper or ink or glue. You’re selling words, arranged into a work of art. Basically, you’re dealing in information.
As such, you need to know when to be able to release information and when to withhold it.
If you’re writing suspense, you always want to give out as little information as possible. It comes on a need-to-know basis. In fact, that’s true for every story, but more so in suspense than in other genres. You have to be secretive when writing suspense, and you have to be careful not to accidentally foreshadow something that’s going to happen, if you want your readers to not see it coming and actually be surprised.
Writing suspense is challenging.
But writing any sort of fiction can be hard…. It’s hard to keep from spilling out all your nicely-planned backstory at once. But that’s exactly what you can’t afford to do. You have to let on to only a little at a time, keeping your readers interested and wondering, who are these people? what are their motives? what are their goals? until they begin to follow the story for its own sake and the sake of its enactors.
Basically, you want to keep them guessing until they’re hooked.
Have fun withholding information!